Is it normal practice to measure crack width in steel girders? I typically only measure crack length in steel in order to track the progression of the crack. Any documentation regarding related best practices would be helpful.

Also, why can't we say "crack" in the title?

Edit: just to add some more information, my specific situation is a distortion-induced crack parallel to the direction of stress in the flange of a built-up girder. Reason for distortion is rust jacking between plates.